Mercury rectifier



June 2?, 1939. HANSELL 2,153,785

MERCURY RECTIFIER Filed April 18, 1936 ac. g OUTPUT XNVENTOR CLARENCE W.HANSELL sYvi g/gmm ATTORNEY Patented June 27, 1939 r UNITED STATESPATENT OFFICE MERCURY RECTIFIER Clarence W. Hansel], Rocky Point, N. Y.,assignor to Radio Corporation of America, a corporation of DelawareApplication April 18, 1936, Serial No. 75,069

4 Claims. (Cl. 175-363) This invention relates to a new and novelmerelements, metering, overload protection, etc., cury vapor rectifierhaving a mercury pool would, of course, be used when desired.

cathode combined with a heated or thermionic In the circuit as shown inthe drawing, the cathode in order to make the rectifier self-startheatedcathode 3 is connected with the mercury 5 ing and to maintain the arcduring operation. pool cathode 4 through a resistance l which a 5 Anobject of this invention is to provide an connects to the midpoint tap 9of filament windimproved self-igniting rectifier and a circuit aring 8,the purpose of resistance l0 being to limit rangement capable ofhandling a large amount the rectified current to a value less than thatof power. of the cathode emission. In effect, the heated 10 Anotherobject of this invention is to provide cathode 3 would serve to startthe discharge in '10 an external current limiting device in the heatedthe tube, but after the discharge is started, then cathode branch of therectifier circuit to limit the mercury pool cathode 4 will carry themain the rectified current in this branch to a value part of the cathodecurrent. Then, if there were which is somewhat less than the limitingsufiicient energy dissipation rating to take care 16 cathode emission,of the losses, a rectifier capable of handling a Although mercuryrectifiers are relatively old very large amount of power output wouldresult. in the art, the mercury pool types require com- In operationwhen thermionic cathode 3 is plicated ignition systems to start andmaintain heated a discharge takes place between this the arc and thethermionic or heated cathode type cathode and anode 2. This dischargecauses an 30 is limited in peak current rating by the electronionization of the gas within the tube and thereby g emission from thecathode. This invention overestablishes the main discharge between themercomes the above-mentioned limitations by the cury cathode 4 and theanode 2. Since the therprovision of both types of cathodes in a singlemionic cathode has a limited electron emission it rectifier with acircuit arrangement which prois necessary that the current flow fromthis vides for carrying the main rectified current to cathode to theanode be limited to prevent the 25 the mercury pool cathode and whichprovides for cathode from being damaged by excessive heating initiatingthe current or are discharge with the and bombardment. The current flowin this path aid of the relatively small heated cathode. is limited bymeans of resistance It in series with The invention will best beunderstood by rethe filamentary cathode and t e Output Ci cuitferring tothe accompanying drawing, which Alternatively, to assist in startingflow of current 30 shows a schematic diagram of the improved tube to themercury pool cathode 4, I may place a and its associated circuit. In thedrawing, the direct current source H5 in series with the currectifierchamber g has the usual anode z and rent limiting impedance In. Thisdirect current mercury pool cathode 4. A second cathode 3 is SOUTCe y bea Small rectifier, p b y o t e located in the rectifier chamber and itis designed Copper oxide or similar type It s to ak to be heated to: anelectron emitting temperature the mercury D001P0SitiVe W sp to theheatby means of electrical heating. The cathode 3 ed Cathode 3 andCauses a flow of current may be a filamentary t directly heated, ortween them. Electrons leaving heated cathode it may be indirectlyheated. Also, it may be 3 strike the surface of the pool of mercury 4and coated to reduce the required temperature f r initiate a dischargefIOIIl the pool 4 to 17118 anode 4O electron emission. In fact, any ofthe electron 2 by Causing emission of Secondary e r s from emittingcathodes commonly used in heated the Surface- The action in this C y becathode gaseous rectifiers may be used. Current Proved by placingcathodfas lfelatively @1059 to the rectifier is supplied from an inputalternattogether and P partlany Shleldmg Cathode 3 ing current sourcewhich is fed into a transfrom th e elecJmc field of the anod? former 5having a primary winding 6, a secondary mi P shows not be ltmltgd to thewinding 1 and a cathode supply winding 8. The 5;. ggf i? a ell-cult gfilament winding 8 may have a midpoint tap 9 1 C p e o a ng 0 er or extt d u d v t m ample, 3, 4, 6, [2, or other members of anodes O W 10h 1sCannes 8 10 e fesls ance j may be used to provide polyphaserectification. 50 output from the rectifier consists of a smoothing Theinvention Should only be limited to Such filter having inductancereactances II and I2 itations as are clearly imposed in the appended andfilter condenser 13, the direct current load 1 being indicated byresistance I4 which may be t i l i s; 5 in the form of a voltagedivider. Other filter 1 A rectifier ir uit comprising an input source, atransformer connected to said input, said transformer having a primaryand a secondary and a cathode heating winding having a central tap, arectifier having an anode, a heated cathode connected to said heatingwinding, and a second cathode comprising a mercury pool, one side ofsaid secondary being connected to the anode of said rectifier, a directcurrent source, a resistance connected from said central tap to saiddirect current source and said second cathode of said rectifier tubewhereby the current flow from said heated cathode to said anode ismaintained within the emission capabilities of said cathode, the outputof said rectifier circuit being connected to the other side of thetransformer secondary winding and to the second cathode of the rectifiertube.

2. A rectifier circuit comprising an input source, a transformerconnected to said input, said transformer having a primary and asecondary and a center-tapped filament winding, a rectifier having ananode, a filamentary cathode having a limited electron emissionconnected to said filament winding, and a second cathode comprising amercury pool, one side of said secondary being connected to the anode ofsaid rectifier, a resistance having such a value that the current fiowfrom said filamentary cathode is maintained within the emissioncapability of said cathode, said resistance being connected from saidcentral tap to said second cathode of said rectifier tube, the output ofsaid rectifier circuit being connected to the other side of thetransformer secondary and second cathode of the rectifier tube.

3. A rectifier circuit comprising a source of alternating current, aload circuit and a rectifier having an anode and a mercury pool cathodewithin a casing, said source of alternating current, said load and saidrectifier being connected in series, a heated cathode within saidrectifier casing, a source of current for heating said heated cathodeand an external resistance connected from said source of current forheating said heated cathode to said mercury pool cathode whereby thecurrent flow from said heated cathode to said anode is maintained withinthe emission capabilities of said heated cathode.

4. A rectifier circuit comprising a source of alternating current, aload circuit and a rectifier having an anode and a mercury pool cathodewithin a casing, said source of alternating current, said load and saidrectifier being connected in series, a heated cathode within saidrectifier casing, a source of current for heating said heated cathode, adirect current source and an external resistance connected from saidsource of current for heating said heated cathode to said mercury poolcathode whereby the current flow from said heated cathode to said anodeis maintained within the emission capabilities of said heated cathode.

CLARENCE W. HANSELL.

